This section is intended to provide a background or context to the invention that is recited in the claims. The description herein may include concepts that could be pursued, but are not necessarily ones that have been previously conceived or pursued. Therefore, unless otherwise indicated herein, what is described in this section is not prior art to the description and claims in this application and is not admitted to be prior art by inclusion in this section.
Location services based on the location of mobile devices are becoming increasingly widespread. Assistance data for assisted navigation systems, such as global navigation satellite systems (GNSS) (e.g., Global Positioning System (GPS), Global Navigation Satellite System (GLONASS) and Galileo) have been specified and standardized for cellular systems. The delivery of such assistance data can be built on top of cellular system-specific control plane protocols including, e.g., the radio resource location services protocol (RRLP) for GSM networks, the radio resource control (RRC) layer of layer 3 in wideband code division multiple access (WCDMA) networks, and IS-801 for CDMA networks, standardized in 3GPP/3GPP2.
The Open Mobile Alliance (OMA) has defined a user plane protocol referred to as secure user plane location (SUPL). SUPL employs user plane data bearers for transferring location assistance information such as GNSS assistance data for carrying positioning technology-related protocols between a user terminal (e.g., a mobile communication device) and its operating network. SUPL is intended to be an alternative and a complement to the existing standards based on signaling in the mobile network control plane. SUPL assumes that a mobile or other network can establish a data bearer connection between a terminal and some type of location server. The use of a user plane protocol becomes especially appealing in case of IP networks where the data bearer is available by nature.
SUPL includes a mechanism for the terminal to report its capabilities to the network element providing assistance. This capability report includes an indication, whether the terminal is capable to perform, for instance, SUPL-enabled terminal (SET) assisted AGPS (Assisted Global Positioning System), SET-based AGPS or E-CID (Enhanced Cell-ID). Moreover, the report contains information on which satellite systems (such as GLONASS, Galileo, etc.) and signals (such as GLONASS L1, GLONASS L2, etc.) the terminal is capable of supporting. This information indicates the network element, which assistance data it can provide the terminal.
The current solution, in which the terminal reports its capabilities to the network, is sufficient for the known purposes, in which there is either:                one terminal and one assistance server providing the terminal assistance data; or        one terminal, one assistance server and the other terminal, of which position the first terminal is able to query.        
In the latter case the first terminal requests the location of the other terminal periodically and the network element queries the position of the other terminal. There is no interaction between the two terminals.
In order to provide advanced Location Based Services (LBS), the first terminal may wish to request the location of the other terminal at certain Quality-Of-Service level (for example, using some particular positioning technology) or request GNSS measurements on certain signals. However, in many instances, the user of the first terminal may be unable to receive necessary information to obtain the desired service.
Similar to SUPL, in OMA SUPL 2.0, when the positioning session is initiated, the SET is required to report its capabilities to the assistance server (SLP). This report indicates the assistance server, which GPS positioning methods (e.g., SET-assisted AGPS, SET-based AGPS, Autonomous GPS), GANSS positioning methods (e.g., SET-assisted, SET-based, Autonomous) and RAN-based methods (e.g., AFLT, E-CID, E-OTD, OTDOA) the SET supports. Moreover, the support for different satellite systems (e.g., such as Galileo, GLONASS, etc.) and signals (Galileo E1, Galileo E5a, GLONASS G1, GLONASS G2, etc.) is reported. However, there is no similar signaling the other way round. This means that the SLP cannot report (and SET cannot request) the SLP's capabilities to the terminal.